From:
Benjamin Chew <000005dbd69f3537-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Subject:
Re: [DCHAS-L] Hydrogen Gas Safety
Date:
Feb 26, 2025 16:49 UTC
Reply-To:
ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID:
<1202129003.2650549.1740588579508**At_Symbol_Here**mail.yahoo.com>
In-Reply-To:
<02dd01db86df$300981c0$901c8540$@verizon.net>
Have you considered the use of a hydrogen generator? Those generate hydrogen from water on demand. They also have a detector in them that senses when there is a significant drop in pressure or change in flow that would indicate a leak and would automatically shut itself down to prevent the room from being filled with hydrogen. You need a source of pure water either to refill the reservoir or to hard plumb into the unit. Maintenance is not too bad - have to change out the media periodically.
There are multiple companies that offer them. We used them on GCs in the lab and kept 1 cylinder of hydrogen as an emergency backup in case the system went down, but much safer than constantly operating on cylinders.
Excess flow shut off valves are always prudent although a properly sized restrictive orifice can also be just as safe. (It also usually allows a smaller size relief device.
While hydrogen can embrittle metals, the line of pure hydrogen regulators is measured in decades. Usually the diaphragm fails long before any other component sees any issues. We finally stopped inspection hydrogen regulators after 20 years of data and found that while an occasional diaphragm failed unexpectedly, the RO and relief device provide adequate protection.
You might want to look at these for more information
Compressed Gases: Managing Cylinders Safely (Chemical Engineering, Oct 2009)
Compressed Gas Cylinder Safety In Research Applications, https://www.linkedin.com/pulse/compressed-gas-cylinder-safety-research-applications-richard-palluzi/
The AICHE publication Handbook for Process Safety in Laboratories and Pilot Plants, (Wiley, 2023) also has a good section on the hazards of compressed gases and how to avoid them.
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Margaret Rakas
Sent: Friday, February 21, 2025 10:18 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [DCHAS-L] Hydrogen Gas Safety
We have 3 different cylinders of hydrogen in use in one lab (different grades for different pieces of equipment ) and have the following questions (I've searched the web but am not sure what is done with relatively small amounts of hydrogen versus a lab that has higher number in use or a 'tank farm' setup.
1) Do you routinely use excess flow shutoff valves? We do have flame arrestors in line with each regulator....
2) How long are regulators (for inert gases as well as hydrogen) used before refurbishing or replacement? Apparently hydrogen gas can embrittle metals...
3) If you send them out for refurbishment I would be interested in knowing where, and how you know their initial age?
thanks very much!
Margaret
--
Margaret A. Rakas, Ph.D.
Lab Safety & Compliance Director
Clark Science Center
Smith College
413-585-3877 (p)
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